Chapter 3 Cells: The Basic Units of Life

Section 1 Organization of Life

Every living thing has at least on cell

Cells: Starting Out Small

ü Most cells are too small to be seen without a microscope

ü Not all act or look the same

§ You have about 200 different kinds of cells

§ Specialized cells – particular jobs

Ex. Bone cells, blood cells, skin cells

Tissue: Cells Working Together

ü Tissue – a group of cells that work together to perform a specific job in the body

Ex. Animal - fat, red blood cells, muscle

Ex. Plants – leaf, leaves

Organ: Teams Working Together

ü Organ – A group of tissues working together to perform a specific job

Ex. Animal - stomach, intestines, heart, lungs, skin

Ex. Plants - stems and roots

Organ System: A Great Combination

ü Organ systems – Organs that work together in groups to perform particular jobs

Ex. Animal -

digestive system, break down food into small particles to be used by your body’s cells, nervous system, transmit information back and forth to your brain and other parts of your body

Ex. Plant – leaf systems, root systems, stem systems

ü Organs depend on one another – if one fails, the whole system is affected

Organisms: independent Living

ü Organism – anything that can live on its own

ü Unicellular – single cell, living on its own

§ So small you need to use a microscope to see

§ Wide variety of shapes and sizes

ü Multicellular – group of cells that must remain together to survive and function as an organism

§ Exists only as a group of cells

§ Most of your cells can survive only if they remain on a part of your body

§ Made of many cells that work together in tissues and organs.

The Big Picture

Organisms interact with each other in many different ways

ü Populations – a group of organisms that are of the same kind and that live in the same area

Ex. p 59 ladybird beetles or red oak trees in a particular forest

ü Communities – Two or more populations living in the same area

Ex. populations of foxes, oak trees, lizards, flowers, and other organisms in a particular forest

**all the people, dogs, cats, trees and flowers in our community

ü Ecosystem – The community and all of the nonliving things that affect it

(water, soil, rocks, temperature, and light)

§ Land ecosystems – terrestrial

Forests, deserts, prairies, your back yard

§ Water ecosystems – aquatic

lakes, rivers, streams, ocean, aquariums